Add spec for LogoutView closes #1613
Implement UserView Skeltons
Add specs for User CRUD Views

closes #1608
closes #1609
closes #1610
Add spec for User#get_absolute_url()
Implement mention models
Implement MensionFactory. Move factory_boy modules
Add specs for Mention models
Add regex to UserCreateForm.

but it haven't been tested yet.
Implement MentionManager and add spec for its method
Add spec for usernames
Add signal to create mention when message was created
Implement mention list API
Add spec for mention list API
Add order of mentions and its test.
Add API make mentions to mark as read
Modify test runner on Travis CI